The inventor has observed that there is a need for improving the safety and ease by which individuals access the roof or top of a vehicle, for example, to remove hay or other objects from a horse trailer, to access items on top of a motor home, and the like. In general, current trailers and motor homes typically have a ladder mounted to a side or rear wall of the vehicle. The ladder includes a frame with upper ends and lower ends that mount to the wall. As a result, the frame is approximately vertical and does not extend to the ground. The prior art discloses numerous other methods of mounting ladders to objects such as vehicles.
For example, U.S. Pat. No. 6,378,654 discloses ladders attached to vertical surfaces, such as a vehicle. The ladder is mounted at its upper end to the vehicle and can pivot outwardly from the vehicle by a scissors-like mechanism at its base that locks the ladder into an extended, inclined position and folds up for a vertical, storage position. The base of the ladder further includes an extension that swings outwardly and downwardly to extend the length of the ladder.
U.S. Pat. No. 6,820,723 discloses a ladder that is pivotally mounted at its base to a mounting frame that rests on the ground as well as being bolted to a vehicle. The ladder is held in a vertically inclined position by a pair of cables extending from a winch in the truck. The ladder is mounted to a mounting frame that appears to be mounted to a trailer hitch of the vehicle.
U.S. Pat. No. 5,469,933 discloses a ladder and frame mounted to a truck. The frame and ladder are assembled adjacent to the truck so that the ladder can be vertically inclined away from the truck. The frame remains attached to the truck and provides stability to the ladder.
U.S. Pat. No. 4,408,680 discloses a ladder that is pivotally mounted at its base to mounting bolts on the bumper of a truck. The ladder is held in a vertically inclined position by a pair of cables extending from a bolt mounted to the bed walls of the truck. The ladder illustrated in the patent is a conventional extension ladder in which two segments slide past each other.
U.S. Pat. No. 2,840,290 discloses a telescoping ladder that is mounted to the roof of a vehicle or a bunk bed. The ladder includes a first section that slides within a second section. The ladder slides within a frame which is mounted to the vehicle roof or bed. The ladder can pivot with respect to the frame with the ladder section extended from until it reaches the ground.
U.S. Pat. No. 2,794,583 discloses a pivoting ladder that is mounted to a printing press. The ladder is mounted to a pair of bolts at its upper end. At its lower end, the ladder is mounted to a pair of bars that are slidably connected to slotted flanges attached to the printing press. The bars may be moved to extend out the base of the ladder.
It also is known to use mobile or portable stairs that have two sections that move relative to each other to allow one portable stair apparatus to be used with platforms of different heights. These portable stairs can be used in numerous applications, for example, in warehouses and box stores to access items stored on high shelves and in the chemical and oil industry to access platforms on chemical processing equipment and oil wells. These portable stairs generally are not permanently fixed to the platform or shelf but instead are moved around as needed to access the elevated shelves or platforms.
Other portable stairs provide the user the ability to purchase one portable stair apparatus and use it with different applications, e.g., a worker in the oil drilling industry may take this from one oil drilling platform to another as need. Thus, the worker may leave the portable stair apparatus on a particular oil drilling platform for one day or months at a time. Notably, the stair apparatus is not permanently fixed or mounted to the platform but instead is retained to the platform by using hooks that clip onto the platform.
These stairs are regulated by the Occupational Safety and Health Administration (OSHA) at 29 CFR 1910.29 (Manually Propelled Mobile Ladder Stands and Scaffolds (Towers)) (2007), which requires that the slope of the steps section be between a minimum of 55 degrees and a maximum of 60 degrees measured from the horizontal. In contrast, OSHA regulations at 29 CFR 1910.24 (2007) for fixed stairs require the angle of the stairway rise to be between 30 degrees and 50 degrees measured from the horizontal. It should be noted that because such stairs are used at a slight angle, it is not typically a problem for the two sections to slide past each other. For example, if the stairs including of sliding sections that are made of aluminum, the two sliding sections will be expected to slide past each other with relative ease and avoid the binding or catching that would be expected if the two sliding sections were at a more extreme angle.